Telephone set add-on accessory stand



FIG. 1 is a front, top and right side perspective view of a telephone set add-on accessory stand showing my new design;

FIG. 2 is a right side elevational view; and

FIGS. 3 and 4 are respectively front and back elevational views;

FIG. 5 is a top plan view; and

FIG. 6 is a bottom plan view. 

The ornamental design for a telephone set add-on accessory stand, substantially as shown and described. 